TON not accumulating

[hinatauchiha]

Hello everyone,

so I added some inputs and 2 TON timers to an existing program that I knew was working just fine before I added these. I verified that each rung was correctly written and would work before I downloaded them, but when I put the PLC in run mode, the timers wouldn't accumulate time even when the rest of the rung was true.

Do you guys have any idea on what could be the problem? It's Micrologix 1200 by the way

Thanks!

(just to clarify, I added two new rungs, both with 4 inputs and one TON timer)

 

[Ron Beaufort]

just GUESSING - but maybe you put the new code into a NEw subroutine/ladder file - and you didn't "call" the subroutine to tell the processor to scan/execute it? ...

if so, you need to add a JSR (Jump to Subroutine) instruction to the Main File (Ladder #2) ...

TIP: with your type of system, only the Main Ladder File (File #2) gets scanned/executed automatically ... any other Ladder Files must be "called" (usually with a JSR instruction) or the processor won't even go there (even though the vertical "rails" might turn green) ...

let us know if this idea doesn't fix your problem - but it's a very common cause for what you've described ...

and welcome to the forum ...

 

[Steve Bailey]

If the timers are in a subroutine, is the subroutine being called?

 

[Ron Beaufort]

(just to clarify, I added two new rungs, both with 4 inputs and one TON timer)

that statement MIGHT mean this:

maybe you have used the same timer ADDRESS (for example T4:0) for more than one timer INSTRUCTION ... in that case, if any one of the TON rungs are FALSE, then that particular TON timer instruction is acting like an RES (Reset) instruction - and effectively "resetting" the other timer instructions on each and every scan ...

the fix for this would be to use a separate address for each timer instruction ... (example T4:0 and T4:1 and T4:2) ...

if nothing else helps you get going - consider posting a screen shot of your code (or the code itself) ...

right now we're just GUESSING at what you're actually seeing ...

good luck with it ...